1. Field of the Invention
The present invention relates to a marking based on chiral nematic (also called cholesteric) liquid crystal polymers. The invention also relates to a method for the modification of chiral nematic liquid-crystal films, in which a chiral nematic liquid-crystal layer is locally or selectively (one or more region(s)) modified with the aid of a modifying composition.
2. Discussion of Background Information
According to a report published by the United Nations Economic Commission for Europe in 2007 the increasing presence of counterfeit goods on the market is costing governments and legitimate traders billions of dollars annually in lost revenues. In addition to the economic impact, counterfeit products or goods with counterfeit conformity assessment marks can also represent serious health and safety problems. Such products may include adulterated or contaminated food, hazardous toys, falsified electrical goods and spare parts for cars. The World Health Organization has identified counterfeit medicines as an enormous threat to health, potentially causing serious harm to patients and sometimes leading to death.
A classic way to protect products or goods from counterfeit is to mark them with a unique identifier. The marking can be in the form of, for example, a code, indicia or a data matrix. Several patent applications relate to marking and apparatus for authenticating them. For example, WO 2003/049047, the entire disclosure of which is incorporated by reference herein, describes a method and apparatus for applying unique composite indicia or makings to a succession of articles, in which each unique composite indicium comprises two or more indicia. At least part of each of the indicia may be co-located at a predetermined location on the article with such co-location being unique or distinct for each composite indicium for each article. The indicium may be overprinted with one or more images, logos or colour-schemes. A code (e.g. an alphanumeric code) that is stored in a database may be derived from the composite indicium from one or more mathematical properties. The code may be later accessed for identifying or verifying the article with indicium. WO 2006/118889, the entire disclosure of which is incorporated by reference herein, relates to an article including a chemiluminescent substance. This document further relates to methods and a device which detect the presence of chemiluminescence for purposes of communicating information associated with the article. Useful applications of the invention include confirmation of the authenticity of an article or its contents, or conversely forgery detection. The method according to the invention relates to an information step providing visible indicia. WO 2009/121605, the entire disclosure of which is incorporated by reference herein, discloses a marking of polymeric liquid crystal material having predetermined optical characteristics allowing its authentication and reading by a machine and its authentication by the human eye. The marking is applied onto an item, good or article. The marking is in the form of indicia representing a unique code which allows for an easy authentication by the human eye and a secure tracking and tracing of the marked item, good or article throughout is life cycle.
Even if the cited methods seem reliable and efficient to protect goods or articles from counterfeiting, it is a fact that counterfeiters use increasingly sophisticated tools to copy and/or replicate an indicium or a marking. This is particularly true when combined with rapidly improving printing technologies such ink-jet, laser techniques etc. There is therefore still a need to create a more sophisticated system having many more chemical and coding permutations than are currently available, without sacrificing the reliability, the ease of use, the ease of production, the ease of detection, the cost of production and authentication.
Thus, it would be advantageous to have available new methods and new markings for tracking and/or authenticating articles using a marking that is easy to apply, detect, read, and decode by an authorized user, and yet possesses a multiple level of coding so as to be extremely difficult to replicate or copy by an unauthorized user or counterfeiter.